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When to Plant Hubbard Squash in Siskiyou County, CA

Siskiyou County, California Zone 8a May

Your May gardening checklist

Welcome to May in Zone 8a. These are the moves that will have the biggest impact on your growing season.

Avg. last frost May 15
Avg. first frost October 1
Soil temp (4") 67°F
Watering Critical
Pest pressure Moderate
Daylight 14.3 hrs
  1. Time to transplant hubbard squash

    Bring a watering can to the bed. Each transplant gets a drink the moment it's in the ground, not ten minutes later.

  2. Put hubbard squash seeds straight in the ground

    Keep the top inch of soil moist until germination — a gentle morning watering for 5–7 days does the job.

Coming up in June — start thinking about
  • Starting indoors: hubbard squash

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Hubbard squash is a large, bumpy-skinned winter squash with dense, sweet, dry flesh ideal for baking and pies. The hard shell allows storage for 6 months or more.

Siskiyou County, California is in USDA Zone 8a. The average last spring frost is May 15 and the first fall frost is October 1, giving you a growing season of approximately 139 days.

At an elevation of 251 feet, Siskiyou County receives approximately 36 inches of rainfall annually with predominantly sandy loam soil. Summer highs average 84°F, so choose short-season varieties of Hubbard Squash to ensure they mature before fall. Sandy soil warms quickly in spring — great for early planting — but Hubbard Squash will need more frequent watering and organic matter to retain nutrients.

Siskiyou County, CA (Zone 8a) Short season
139 days
Last Spring Frost May 15
139 growing days
First Fall Frost October 1
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Siskiyou County Soil Profile

Soil Type

Sandy Loam

Soil pH

6-6.9

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✗ May not fit
Start indoors: Apr 8 Transplant: May 20 🍅 Harvest: Sep 2 – Oct 7
Recommended (50%) ✗ May not fit
Start indoors: Apr 17 Transplant: May 29 🍅 Harvest: Sep 11 – Oct 16
Safe Start (90%) ✗ May not fit
Start indoors: May 21 Transplant: Jul 2 🍅 Harvest: Oct 15 – Nov 19

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Siskiyou County

How your county's soil matches Hubbard Squash's growing requirements.

Soil pH

Your soil pH (6.0–6.9) is within Hubbard Squash's preferred range (6.0–7.0).

Soil Texture

Sandy soil in Siskiyou County warms quickly in spring but drains fast. Hubbard Squash will need more frequent watering and regular compost additions to retain nutrients.

Organic Matter

Organic matter is moderate (2.5%). Annual compost additions will help Hubbard Squash.

How to Plant Hubbard Squash

1"
Planting Depth
30"
Between Plants
42"
Between Rows

Plant Water Budget

Plant needs
1.0″/week
Rainfall provides
1.1″/week
Watering frequency Natural rainfall sufficient
Season total 0 gal / 100 sq ft

Monthly Watering Guide for Hubbard Squash

Hubbard Squash needs approximately 1 inches of water per week (4.3" per month). Here's how your county's rainfall compares month by month.

Month Hubbard Squash Needs Rainfall You Supplement Action
Jan 7.3" 0" ❄️ Dormant
Feb 7.1" 0" ❄️ Dormant
Mar 5.3" 0" ❄️ Dormant
Apr 3.3" 0" ❄️ Dormant
May 4.3" 1" 3.3" 🚿 Regular watering
Jun 4.3" 0.2" 4.1" 🚿 Regular watering
Jul 4.3" 0" 4.3" 🚿 Regular watering
Aug 4.3" 0" 4.3" 🚿 Regular watering
Sep 4.3" 0.4" 3.9" 🚿 Regular watering
Oct 4.3" 1.6" 2.7" 🚿 Regular watering
Nov 3.1" 0" ❄️ Dormant
Dec 6.7" 0" ❄️ Dormant

Water needs are for active growing months only (May–Oct in Siskiyou County). Supplement amounts are based on average rainfall — actual needs vary with temperature, soil, and mulching.

Hubbard Squash Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" — every day above 50°F deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Hubbard Squash needs ~1,430 GDD — county provides 1,807 GDD Good fit

Hubbard Squash Planting Timeline — Siskiyou County, CA

Hubbard Squash Planting Calendar

Activity When Date Range
Start Indoors April 17 Apr 17 – May 1
Transplant Outdoors May 29 May 29 – Jun 12
Direct Sow May 22 May 22 – Jun 12
Harvest September 11 Sep 11 – Oct 16

Plant 1" deep · 30" apart · Rows 42" apart

Month-by-Month Timeline

MonthActivities
January
February
March
April Start Indoors
May Start Indoors Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow
July
August
September Harvest
October Harvest
November
December
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Growing Conditions

☀️ Sun

Full Sun (6-8+ hours)

💧 Water

1"/week · Natural rainfall sufficient

📅 Days to Maturity

100–120 days

🧪 Soil pH

Needs 6–7 · Your soil: ideal

🗺️ USDA Zone

Zone 8a

📆 Growing Season

139 days in Siskiyou County

Growing Tips for Hubbard Squash in Siskiyou County

Direct sow Hubbard Squash outdoors after May 15 in Siskiyou County when soil has warmed and frost danger has passed.

Sandy soil in Siskiyou County dries quickly — mulch Hubbard Squash with 2-3 inches of straw and water deeply 2-3 times per week rather than lightly every day.

Common pests for Hubbard Squash in this region include squash vine borer and cucumber beetles. Use row covers early in the season and inspect plants weekly.

General growing tips

Start seeds indoors in short-season areas. Requires ample space and rich soil. Harvest when the skin is very hard and the color is deep. Cure in the sun before storing.

Companion Planting

Good Companions

Avoid Planting Near

  • Potatoes

Check more plant combinations with our Companion Planting Checker →

Frequently Asked Questions

When should I plant Hubbard Squash in Siskiyou County, CA?

Siskiyou County is in Zone 8a with an average last frost of May 15. Plan your Hubbard Squash planting based on this frost date — see the calendar above for exact timing.

What planting zone is Siskiyou County, CA?

Siskiyou County, California is in USDA Hardiness Zone 8a. The average last spring frost is May 15 and first fall frost is October 1.

🌱

Your Siskiyou County Garden Planner — Free

A 24-page printable planner built for Siskiyou County (Zone 8a). Planting dates, a month-by-month schedule, harvest log, seed inventory, and succession charts — all dialed in for your exact growing season.

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Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Siskiyou County, CA. Local conditions may vary. Last updated: May 2026.

Sources & credits

Every number on this page traces back to a primary horticulture or government data source. Click through to verify.